The present invention is directed to the field of replacement mufflers, and more specifically to the field of replacement mufflers which can be used to replace original equipment mufflers without requiring any substantial modifications thereto.
It is well known that automotive exhaust systems, and in particular mufflers, are subject to a great deal of physical and thermal stress, and as a result must often be replaced. Indeed, the muffler replacement industry is quite large.
It has been the practice of the larger muffler replacement companies to stock a full line of replacement mufflers which are substantially identical to the original equipment mufflers. By doing so, the original muffler may typically be replaced by separating the tubes or "nipples" on both sides of the muffler from the exhaust and tail pipes, and by reattaching a substantially equivalent structure to the respective pipes. In some cases however, the downstream nipple is not attached to a separate tail pipe, the downstream nipple itself forming the tailpipe or spout. In such case the original muffler is replaced by separating the upstream nipple from the exhaust pipe and by reattaching the substantially equivalent structure thereto. In either case, the resulting exhaust system is essentially a duplicate of the original system. As used throughout the specification and claims, the term "nipple" will be deemed to include the tubes on both sides of the muffler, whether they are attached to exhaust or tail pipes, or whether they form an exhaust pipe or spout without further connection to an external pipe.
Although the above-described technique is relatively simple to accomplish, it is expensive since it is necessary to produce and stock from 600 to 800 different kinds of mufflers in order to substantially duplicate the original equipment mufflers for the various makes and models of domestic and foreign automobiles. Further, the storage and inventory requirements are indeed prohibitive for all by the largest replacement muffler manufacturers and installers. Still further, since each type of muffler must be made from scratch and requires a significant re-tooling of the assembly line, a long lead time is many times required when ordering a particular muffler.
A technique for avoiding the problems associated with the above-described procedure had been developed in the early 1970's and employed the use of a "universal" muffler which could be used to replace the original equipment on a wide range of vehicles, thus reducing the inventory and storage requirements associated with the above-described procedure. Briefly, the universal mufflers employed a muffler body which was roughly of the same size and shape as the original equipment muffler, but which in no way had to be an exact duplicate of the original. A first type of universal muffler employed nipples which were slidably disposed within the muffler body to effect different length connections between the exhaust and tail pipes. An example of such a system is disclosed in U.S. Pat. No. 3,581,842 to Hall.
Another type of universal muffler employed nipples produced from drawing quality aluminum killed steel, at least one of which was produced with a longer than average length. The muffler would be placed between the exhaust pipe and the tail pipe and if the distance between the two were significantly less than the nipple-to-nipple length of the muffler, the extended length nipple could be trimmed so as to allow the muffler to fit between the exhaust and tail pipes. Further, if it were found that the diameters of the exhaust and tail pipes were too large for the nipples provided on the muffler, the nipples could be opened up to a wider diameter by swaging or otherwise expanding. Examples of such mufflers are disclosed in U.S. Pat. No. 4,164,267 dated Aug. 14, 1979 to Meineke et al., which has since been dedicated to the public, U.S. Pat. No. 4,279,326 dated July 21, 1981 also to Meineke et al., and in the American Muffler Corporation Exhaust Parts Catalog cited in U.S. Pat. No. 4,279,326.
Thus, although the "universal" muffler could be used on a wide range of automobiles, the installation thereof is somewhat time consuming, and the replacement was not as aesthetically acceptable as that associated with a "made-to-fit" replacement. Further, the use of the universal mufflers required specialized apparatus, such a swaging tool for increasing the nipple diameters if necessary.